Even though the following discussion is applicable to the aforementioned other uses, it is written in the vernacular of terms relating to a typical oil burner. This invention relates to a device the objective of which is to isolate and minimize the effects of downdraft on the efficient operation of an oil burner. Modern furnaces and boilers are fired with high efficiency types of oil burners. These burners rely upon their maximum combustion efficiency by the thorough mixing and firing of the precise quantity of air and fuel oil. This optimum air-fuel ratio is achieved after a series of tests in which the following flue gas parameters of smoke stack draft, smoke spot number, smoke stack temperature, and carbon dioxide are measured and recorded respectively. The results of said tests are then studied and an appropriate adjustment is made to one or more of the aforementioned parameters and the process is repeated until a high combustion efficiency is achieved. Even though each of these parameters are important and interrelated for maximum fuel economy, the draft and air-fuel ratio settings are the most important and if said settings are not properly adjusted and kept regulated during varying draft conditions, poor oil burner efficiency will result as well as a number of other undesirable side effects such as soot, smell and noxious fumes. Presently, in an attempt to maintain a constant and well regulated negative chimney draft and offset any said pressure fluctuations, oil fired boiler smoke stacks are installed with a draft regulator which is adjusted to some optimum negative pressure, usually specified in terms of "inches of water." This device is simple, responds to varying natural draft fluctuations, and usually consists of a swinging gate type of air modulator which works on the principle of a counterbalance and a negative draft. The counterbalance is that component of the draft regulator which is adjustable and is used to set the negative draft to some nominal value. The objective of this device is to maintain a steady regulated negative boiler breech draft by allowing a proportional input of room positive air pressure through the draft regulator to mix with the varying negative chimney draft pressure and compensate for any condition of surging negative draft caused by varying wind conditions passing over the chimney. However, some conditions of wind in combination with chimney locations can have an adverse effect on the natural chimney draft and without any applied compensation, can cause a downdraft or a positive pressure to travel down the chimney, through the boiler, and reach the oil burner. By reason that, since the simple said draft regulator commonly used today opens on an excess of chimney negative pressure; then conversely, so will it close upon exposure to a positive pressure. Thus, with the said gate forced closed, the said draft regulator will cease to perform its basic function and allow the said adverse positive pressure be reflected down and into the boiler. At this point, the burner-boiler combination will be completely subject to positive downdraft with the resulting mismatch of air-fuel ratio and consequential faulty burner operation. The principles of a negative draft regulator and the results of their applications have been described only at a cursury level for the purpose of introducing background information to illustrate the inadequacies of the present draft regulator to compensate for a downdraft condition.